A skyway was similar to a highway, with airspace set aside for the general public to drive flying vehicles. Signs and lane markers for the skyways floated in the sky; how, exactly, these remained in the air is unknown, whether it be by antigravity mechanisms or magnetism, but no thrust was involved. Skyways were constructed throughout the planet sometime after 1985, and were in full operation in 2015. Local skyways connected to hyperlanes with access to major international cities on other continents. The hyperlane closest to Hill Valley offered access to Phoenix, Boston and London. Floating signs would indicate exits, destinations, and even travel conditions for the skyway, including winds, weather, and even ozone.
In the novelization, Air Traffic Controllers are employed to actively monitor the skyways to notify drivers of infractions of air traffic laws. All flying cars are equipped with transponders to help computers regulate the flow of traffic and for controllers to contact drivers to notify them of infractions. Other standard equipment for flying vehicles were eyewear that gave live video feed behind the vehicle to the driver and a communications headset.
After departing from Lyon Estates in 1985, the DeLorean appeared in the middle of Skyway C25 in 2015, but in the wrong lane and facing oncoming traffic. Doc had to lie to an air traffic controller about a broken transponder to cover for this mistake. There were separators between the lanes, and these could move if necessary to avoid a collision, albeit returning to a fixed location in the sky. Doc brought the vehicle down, under the lane markers, and back up again into the right lane. Upon reaching the exit 'ramp' that spiralled down into Courthouse Square, Doc landed the car in an alley. The skyway was visible from the square after the scheduled rain showers ended.
Same-way traffic seems to have flowed in multiple imaginary boxes one on top of each other. The equivalent of a traffic jam was if the skyway was "skewed", with traffic being unable to move in any direction – forward, backward, up or down. On October 21, 2015, the skyway from the Courthouse Mall to Hilldale was skewed, and even after departing during daylight, travelers that evening (the police, Doc and Marty, and a taxicab ferrying Biff) were not able to reach Hilldale until after dark.
After Marty and Doc carried Jennifer from the house in Hilldale, they prepared to return to the past, unaware that Biff had altered history. It appears that speeds were very fast on the skyway, at least 80 miles per hour, as Doc had to accelerate only slightly in order to reach 88 miles per hour when traveling from 2015 to 1985A. Whether the blinding flash from time displacement, or the remaining fire trails, had any effect on traffic in 2015, is unknown. When the DeLorean arrived back in 1985A, it was at an altitude that placed it slightly below the flight path of a descending commercial airliner.